Disc brake pad mounting and retention system and method

ABSTRACT

A system and method are provided for mounting, removing and retaining brake pads in disc brakes, such as air-operated disc brakes utilized on commercial vehicles, in a manner which does not require the use of separate brake pad retaining devices while providing positive retention of the brake pad. A preferred embodiment includes a brake caliper mount having brake pad abutment surfaces having radially-oriented and lateral grooves which permit a brake pad with corresponding projections on is lateral sides to be inserted through an opening of the brake caliper into the radially-oriented grooves until the backing plate projections are aligned with the lateral groove, and advancing the brake actuator behind the brake pad to place the brake pad in an operating position in which the actuator prevents the brake pad from realigning with the radially-oriented grooves until the actuator is retracted to permit brake pad extraction.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to disc brakes for vehicles, and inparticular to a system and method for mounting, removing and retainingbrake pads in disc brakes, such as air-operated disc brakes utilized oncommercial vehicles.

Pneumatically-operated disc brakes have been undergoing development anddeployment on commercial vehicles since at least the 1970's, and arebeginning to replace drum-style brakes due to advantages in areas suchas cooling, fade resistance and serviceability. German PatentPublication No. DE 40 32 886 A1, and in particular FIG. 1 of thisdocument, discloses an example of such an air disc brake. In thisdesign, a pneumatic diaphragm chamber (pneumatic actuator) is attachedto a rear face of the disc brake caliper housing, and applies a brakeactuation force through a linear actuator rod to a brake actuator leverwithin the caliper. The brake's actuator lever in turn transfers andmultiplies the force applied by the actuator rod to one or morespindles, which force brake pads against a brake disc or rotor. Theterms “brake disc,” “rotor” and “brake rotor” are used interchangeablyherein.

As shown in FIG. 1 of DE 40 32 886 A1, the actuator is located inboardof the brake caliper, in large part because commercial vehicle wheelrims are sized to only provide adequate clearance for the drum-typebrakes historically employed on such vehicles. Because the resultingspace envelope between the wheel and its axle is limited, the actuatormust be located into the space adjacent to the wheel. For the samereason, brake pads must be configured to conform to the limitedavailable radial space, and thus have typically been located andretained on one of the brake caliper or brake caliper carrier/mountusing transverse suspension pins and/or using leaf spring-type metalstrips disposed over the outer radius of the brake pads. Brake pads havealso been retained by capturing the brake pads between the calipermounting frame and the portion of the brake caliper which straddles thebrake disk. (As one of ordinary skill will recognize, the same brake padsupport function may be provided by a brake caliper carrier/mountdesigned to support the brake pads or by a brake pad carrier which isseparate from the caliper mounting structure. For convenience in thisdescription, the terms caliper carrier, caliper mount and brake padcarrier may be interchanged without intending to limit the brake padsupporting structure to any specific brake pad and brake calipercarrying structure.)

Conventional commercial vehicle air disc brakes have typically requiredthe installation of ancillary brake pad retention mechanisms, and/or useof the brake caliper itself to retain the brake pads during service.Both of these approaches, and in particular use of the brake caliper asthe retention means, requires disassembly of the pad retention mechanismand/or removal of the brake caliper in order to replace worn brake padsand install new brake pads. As a result, brake pad replacement inprevious air-operated disc brake designs has been a labor-intensive, andtherefore costly, process.

A further problem with prior art brake pads is the tendency for thebrake pad to rotate and/or vibrate during brake operation. Asillustrated in. FIG. 6, when a brake pad 101 is applied against afriction surface of a brake disc (not illustrated) which is rotating indirection DR, the brake disc rotation induces motion and reaction forcesbetween the brake pad 101 and its adjacent mount abutment surfaces(notillustrated for clarity). Specifically, at the leading edge 102 of thebrake pad the brake pad attempts to move upward in direction LU inresponse to the friction forces along the face of the brake pad(illustrated here by force arrows across the face of brake pad 101). Atthe trailing edge 103 of the brake pad, the brake pad attempts to movedownward in direction TD. However, because the brake pad 101 isconstrained by adjacent mount abutment surfaces, the overall motion ofthe brake pad is generally a rotation about an axis parallel to thebrake disc rotation axis. This motion may be unilateral during the brakeapplication, or may manifesting itself as a moderate-to-severeoscillation of the brake pad in its mount, significantly increasing wearof the abutting brake pad and mount surfaces.

In order to prevent undesired rotation and/or vibration of the brake padwithin its mounting (for example, rotation about the brake applicationdirection), the brake pad backing plate and the adjacent mountingbracket horns supporting the brake pads in the circumferential directionrequired a relatively tall radial height to minimize the amount of brakepad rotation before a corner of the backing plate contacted the adjacentmount horn (a motion referred to as “pad kick” r “pad turnout”). Thisrelatively tall structure in turn would require the brake caliper, whichis installed over the brake pads and mounting bracket, to have itscorresponding opposing inner surfaces radially outboard of the mounthorns be relieved enough to accommodate the outer corners of the brakepad and/or mount horns. A problem with this thinning is that because themaximum outer radius of the brake caliper is typically constrained byvery tight clearance to the inside of the adjacent wheel rim, the brakecaliper arms straddling the brake disc between the application side andthe reaction side of the caliper may end up being thinner than desiredin this region in order to accommodate both the tall carrier mount hornand the close-fitting wheel rim. This can lead to very high tensile andbending stresses in the thin region, and an undesired reduction infatigue life and service lift.

The present invention addresses these and other problems by providing abrake pad mounting and retention arrangement and method of installationand removal which provides greater ease in in-situ brake padinstallation and removal, without brake caliper removal or othersignificant brake disassembly work. This solution is of particularsignificance in highly space-constrained commercial vehicle air discbrake applications, where brake pad servicing without significant brakecaliper disassembly work was not previously believed to be commerciallypractical.

In one embodiment of the present invention the brake caliper mount padsupport horns are provided with a narrow vertical groove or slot on theside of the horns facing away from the brake disc. This groove isarranged to permit the brake pad, having features of correspondingthickness on its lateral sides, to slide in the radially-inwarddirection down the groove, until the brake pad reaches the installedposition. The horns further have lateral grooves at or near their basesextending parallel to the brake disc rotation axis, arranged to receivethe side features of the brake pad, such that the brake pad may advancetoward the brake disc when pushed forward by the brake caliper'sactuator. During service, the brake pad is positively retained in thebrake by the combination of: (i) the lateral grooves in the mount horns,preventing lifting of the brake pad out of the caliper and unduerotation of the brake pad (i.e., twisting or “tipping” of the pad in thecaliper as the rotating brake disc attempts to raise one end of thebrake pad while pushing down on the other end of the brake pad); (ii)the brake disc, which prevents the brake pad from advancing so far as toemerge from the mount horn lateral grooves; and (iii) by the brakeapplication device, which prevents the brake pad from retreating so faras to reach the mount horn vertical grooves and slide out the top of thecaliper.

This arrangement also facilitates easy and rapid brake pad changes, asall that is required to remove the brake pads after wheel removal is tofully withdraw the brake application device, slide the brake pad backingplate axially to reach the mount horn vertical groove, and then simplylift the brake pad out of an opening in the top of the still-installedbrake caliper. A new brake pad may then be inserted into the verticalgroove until the backing plate's lateral features are aligned with thelateral grooves, followed by advancing the brake application device asufficient distance behind the brake pad to prevent its backing out ofthe lateral grooves.

The present invention also provides the ability to significantly lowerthe height of the mount horns, thereby permitting the brake caliperthickness in high-stress regions to be made thicker to increase strengthand caliper service life. The geometry of the relatively compact groovesand corresponding engaging features on the brake pad backing platesensures the amount of brake pad rotation within the carrier issignificantly limited as compared to prior art arrangements.Accordingly, because there is no longer a need to provide relativelytall mount horns to limit pad rotation (as the grooves now limit padrotation), the horns may be made shorter. With the reduction in hornheight, the newly-found additional clearance between the horn and theinner surface of the brake caliper in the regions over the horns allowsthe caliper to be made thicker in these highly-loaded areas. Theaddition of caliper material in these regions provides additionalload-bearing cross-sectional area, with corresponding reduction in localstress levels and increase in caliper fatigue life.

Preferably the brake pad, mount and/or brake caliper may be providedwith vibration-damping features, such as spring-loaded brackets on thebacking plate lateral extensions or a spring member engaging tabs on theupper surface of the backing plate and on the caliper or caliper mount.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view of a disc brake in accordance with anembodiment of the present invention.

FIG. 2 is an oblique view of the caliper mounting carrier and brake padof FIG. 1.

FIGS. 3 a, 3 b and 3 c are side, front and top views, respectively, ofthe brake pad of FIGS. 1 and 2. FIG. 3 d is a detail view of anembodiment of a pad retention feature shown in FIG. 3 b.

FIGS. 4 a and 4 b are elevation and front views, respectively, of thecaliper mounting carrier of FIGS. 1 and 2. FIG. 4 c is a cross-sectionview of the caliper mounting carrier of FIGS. 1 and 2 showing anembodiment of mount horn brake pad guiding and retaining grooves.

FIG. 5 is a detailed view of a pad retention feature including apre-loading device in accordance with an embodiment of the presentinvention.

FIG. 6 is a schematic view of motions and forces resulting fromapplication of a brake pad to a rotating brake disc.

FIGS. 7 a and 7 b are views of an alternative embodiments of a brake padwith pad retention features at a lower surface of the brake pad.

FIGS. 8 a and 8 b are views of an alternative embodiment of a brake padwith asymmetrical and rotation-accommodating pad retention features.

DETAILED DESCRIPTION OF THE DRAWINGS

In the embodiment shown FIG. 1, a disc brake 1 of a commercial vehicleincludes a brake disc 2, a brake caliper 3 straddling the brake disc 2.The caliper 3 is affixed to a caliper mounting carrier 4 which in turnis fixed to a vehicle axle, typically via a torque plate or a brakespider (not illustrated). The caliper 3 is actuated by an actuator 5, inthis embodiment a spring brake actuator which is controlled by pneumaticpressure from the vehicle. The actuator 5 acts upon a brake padapplication mechanism contained within caliper 3 to press brake pads 6against the brake disc 2 to slow the vehicle. The present invention isnot restricted to a pneumatic actuator (for example, anelectrically-driven actuator may be used) or to a particular type ofbrake caliper/mount arrangement (for example, a fixed carrier and asliding caliper with a single-side brake pad application mechanism, or afixed carrier and fixed caliper with two-sided brake pad applicationmechanisms). In this embodiment the caliper 3 is provided with anaperture 7 which is wide enough in the circumferential direction A andthe axial direction B to permit the brake pads 6 to be withdrawn andinserted without removal of the caliper 3 from the carrier mount 4.

FIG. 2 shows an oblique view of the carrier and brake application-sidebrake pad of FIG. 1, with the brake disc 2, caliper 3, actuator 5 andopposing brake pad 6 removed for clarity. In this view and in FIGS. 4a-4 c, there are illustrated the holes 8 in mount 4 for receivingcaliper and axle mounting bolts, as well as the lateral brake padengagement surfaces 9 on mount horns 10. It will be appreciated that thecarrier need not be a caliper-supporting carrier, i.e., the caliper maybe mounted on a component separate from the carrier, with only the brakepads being carried by the carrier.

Each of the mount horns 10 in this embodiment has a vertical brake padinstallation/removal groove 11, and a horizontal brake pad guidinggroove 12 at the bottom of each mount horn 10. It will be appreciatedthat the grooves or slots need not be located at the farthest axiallocations on the carrier mount 4 away from the brake disc 2, orprecisely at the bottom of the mount horns 10, as long as the brake pad6 to be used in the brake is blocked from escape from the carrier mount4 during in-service use and has pad retaining features with a verticalheight corresponding to the height of the horizontal grooves 12. In analternative embodiment, the vertical installation/removal groove 11 maybe omitted, as long as sufficient space is provided in the caliperaperture in the direction of the brake disc rotation axis to permit thebrake pad to be inserted radially inward into the brake, such that theretention features of the brake pad may reach and enter the horizontalgrooves 12.

FIG. 2 and FIGS. 3 a-3 d show the brake pad 6, comprising a brake padbacking plate 14 and brake pad material 15 affixed to the brake discside of the brake pad 6. The brake pad material 15 is arranged to fitbetween the mount horns 10 without engaging the grooves 11 or 12 toensure free movement toward and away from the brake disc 2 andvertically in and out of the caliper during brake pad installation orremoval. The brake pad 6 is also provided with pad retention features 16at the lower corners of the lateral sides of the backing plate 14. Inthis embodiment the retaining features 16 are arranged as tab-likeextensions of the backing plate 14. Preferably the tabs have a thicknessin the brake application direction corresponding to the thickness of thebacking plate 14, so that no special machining or other forming forwidth reduction are needed. In any event, whatever the thickness of thepad retaining features 16, the vertical grooves 11 must have an axialthickness and a circumferential width large enough to accommodatevertical passage of the pad retaining features 16 during insertion andremoval of brake pad 6. Similarly, the lateral or axial grooves 12 musthave a vertical height and a circumferential width large enough toaccommodate horizontal passage of the pad retaining features 16 duringin-service brake application and release and during movement away fromthe brake disc 2 during removal of brake pad 6. Preferably, the lateralgrooves 12 are located toward the radially-inner portion of the calipermount 4, where the carrier is more stiff.

In addition to the preferred arrangement with male pad retainingfeatures extending laterally into female lateral receiving grooves,female slots in the lateral sides of the brake pad backing plate may bea arranged to receive corresponding male projections from the calipermount after the brake pad is inserted into the disc brake along theradially-oriented grooves. Alternatively, the female lateral receivinggrooves may be placed directly on the caliper body, with or withoutcorresponding features on the caliper mount. Additional example padretention feature arrangements are discussed further, below.

Also visible in FIGS. 3 b and 3 c is a groove 18 on the brake pad 6 forreceiving a brake pad wear indication sensor (not illustrated).

FIG. 3 d shows a detailed view of the region of brake pad 6 highlightedin area C of FIG. 3 b. In this region the brake pad retaining feature 16is provided with a bevel, chamfer or rounded contour 19 at its loweredge to facilitate jam-free insertion and removal of the brake pad andto avoid developing a stress-concentrating contact point between theretaining feature 16 and the carrier mount 4 within groove 12.Preferably, a corresponding mating feature is provided on the carrier toreduce stress concentration. The pad retaining feature 16 is alsoprovided with a bevel 20, preferably set at an angle corresponding to asimilar angle at the top of horizontal groove 12. The upper bevel 20 isprovided to present a larger bearing surface, and therefore lowercontact pressures and stresses, as brake application forces aretransferred from the brake pad 6 to the carrier mount 4 during brakeapplication, a time when the brake disc 2 drives the brake pad 6 torotate in the carrier mount 4. Inclusion of bevel 20 provides a planarsurface to absorb forces over a broader contact area to minimizecomponent wear, thereby preferably avoiding point or edge contactbetween the brake pad 6 and the carrier mount 4 which may occur withopposing rectilinear surfaces.

The angle of the bevel may be set to ensure that the contact pressuregenerated during maximum brake pad loading is below the yield strengthsof the brake pad backing plate and the carrier mount materials. If theloads to be supported during brake application are relatively low, ashallow bevel angle on the order of 95-110 degrees may be sufficient toprovide enough contact area on top of the bevel so that the stress level(force area) is below the yield strength of the components. In the caseof higher loadings or use of materials with lower yield strengths, alarger angle, on the order of 110-165 degrees may be required to providea large enough contact area over which the load is distributed to remainbelow yield strength limits. An angle between 140-160 degrees,preferably 150 degrees, provides a large contact area while stillminimizing the amount of pad “lift” or rotation during brakeapplication.

A significant benefit of the pad retention arrangements of the presentinvention is evident in this embodiment. In the prior art, due to theneed to maintain at least minimal clearances between the flat opposingfaces of conventional straight-edged brake pads and their opposing mounthorn abutment surfaces, the mount horns and brake pad mounting platefaces had to be relatively tall in order to minimize the extent to whichthe brake pad could rotate about the axial direction B when the brakewas applied. With the current state of the art, due to the distance fromthe diagonally opposite corners of the brake pad, the typical tolerancesbetween the brake pad backing plate and the mount horns would result arelatively large degree of undesirable pad rotation within the mountunless tall mount horns were provided to minimize the angulardisplacement of the brake pad. In the present invention,because theretaining features interact with the relatively small horizontal grooves12, even with the same minimum brake pad/mount horn clearancerequirements as in a conventional prior brake, the brake pad 6 cannotrotate nearly as far as a conventional brake pad before the uppersurfaces of the pad retaining features 16 meet the top of horizontalgroove 12 and halt the angular displacement of the brake pad 6.

For example, a typical prior art brake pad and retention arrangementwould allow on the order of 4 mm of movement, leading to largedisplacement vibrations and accelerated war of abutting surfaces of thepad backing plate and the mount horns. With the present invention, thesemovements may be reduced by 75% or more. Experiments with sampleconfigurations have demonstrated movements being limited to as little as0.75 mm. As a consequence, because pad rotation management has beentransferred from the top edges of the mount horns to the horizontalgrooves 12, the mount horns do not need to be as tall as previouslyknown in order to control brake pad rotation o a desired extent. This inturn permits avoidance of undesired thinning of the brake caliper in theregions above the tops of the mount horns, thereby allowing these veryhighly loaded and stressed regions to have a greater cross-sectionalarea to absorb these loads. The lower stresses directly correspond toincrease caliper strength and increased caliper fatigue life, despitethe very constrained wheel rim environment of a commercial vehicle. Theimprovement in stress-bearing volume of material may also enablereplacement of costly specialty alloys used to obtain sufficientstrength in the thin sections of the caliper with common cast iron,significantly reducing material and production costs. It should be notedthat although the amount of “pad kick” may be lower in the presentinvention, when the bevel angles of the brake pad retention features andthe corresponding lateral grooves are selected, the angles may differslightly to accommodate the pad rotation under braking, e.g., the padretention feature angle may be slightly more obtuse than the mount'slateral groove bevel, so that when the pad rotates in the mount, thecontact faces make contact across a planar area, rather than alone asingle line of contact.

A further advantage of the present invention is that it permits theelimination of retaining leaf spring interlocking features on the top ofthe brake pad backing plate, as well as associated structures radiallyabove the brake pads to receive and retain the leaf springs (e.g., a padhold down bar), thereby increasing radial clearance above the brake padand potentially permitting either a decrease in the greatest radialextent of the caliper within the wheel envelope, or increase in thediameter of the brake disc and pad height to increase the size of thebrake swept area where the brake pad material interacts with the brakedisc surface.

The present invention's pad retaining features may also be provided withspring elements at or near the pad retaining features to desirablypre-load or dampen the pad relative to the mount, to reduce pad motionand reduce vibrations which may induce undesired noise and componentwear during brake application. FIG. 5 shows a detailed of an examplearrangement, wherein a spring element 22 is located between the brakepad backing plate 14's pad retaining feature 16 and the outer wall oflateral groove 12. Such a pre-loading element may be affixed to eitherthe mount 4 or the brake pad backing plate 14, for example by rivetingor clipped on, or may be a separate element inserted between the mount 4and the backing plate 14 when the pad 6 is inserted into the brake.Alternatively, the pre-loading element may have any of a number ofsuitable arrangements, such as a hinged member provided with a springelement which biases the hinged member laterally outward to engage theopposing surface.

A further embodiment of the present invention is illustrated in FIGS. 7a-7 b. In this embodiment, the pad retention is achieved with tabs 16located on a lower edge or surface of the brake pad backing plate 14,with an undercut groove on at least one lateral side of the tab whichengages a corresponding undercut groove in horizontal receiving groove12. In this embodiment groove 12 is machined into the lower surface ofcaliper mount adjacent to the vertical pad abutment 10, rather thanlaterally across the face of the abutment. As with the foregoing exampleembodiments, this bottom tab embodiment is inserted vertically (i.e.,radially inward) along the outsides of the abutments 10, then advancedinto engagement with grooves 12 toward the brake disc to positivelyretain the brake pad.

FIGS. 8 a and 8 b illustrate another embodiment of the presentinvention, in which the pad retention features are asymmetrical, and arealso configured to accommodate the brake disc-induced brake pad rotationwith minimal pad movement and minimum pad and abutment surface wear.FIG. 8 a shows a brake pad backing plate 14 with a beveled tab 16 on theleading edge side of the brake pad, and a curved tab 16A on the trailingedge side of the brake pad. This configuration provides a number offurther advantages, including a configuration which inherently preventsthe brake pads from being installed on the wrong sides of the brake discdue to the incompatibility of the corresponding grooves 12 in which theyslide. The curved surface also forms a “ball-and-socket”- or“cylinder-and-socket”-like bearing arrangement with its correspondinggroove 12, thereby providing a broad surface area for contact betweenthe brake pad tab 16A and groove 12 which lowers contact face stressesand resulting component wear. The curved surface may also further reducethe amount of brake pad motion (“pad kick”) by more tightly limiting therange of motion of the trailing edge of the brake pad, with the curvedtab 16A potentially acting as a nearly fixed point of rotation aboutwhich the leading edge tab 16 rotates. This nearly-fixed trailing edgeconfiguration acting essentially as a pivot, also provides additionalresistance against brake pad motion becoming so great as to inducelarge-amplitude vibrations.

As shown in FIG. 8 b, the trailing edge tab 16B may be a large radiuscurve, further spreading reaction force loads over a broader contactarea. The curvature of the trailing edge tab is not limited to curves ofconstant radius. For example, the curves may be configured withdecreasing or increasing radii, for example, to further define themotion of the trailing edge of the brake pad during brake application.Alternatively the curves maybe polygonal in shape. As with all of theembodiments of the present invention, these shapes may be economicallyformed, for example by lateral machining of the grooves 12 across thefaces of the mount abutment surfaces with suitable tooling.

As with the previous embodiments, it may be preferable to account forpad rotation under braking in the brake pad backing plate design and/orthe mount arrangements. For example, where the curved retention featureis on the trailing edge of the brake pad, in order to accommodate the“lift” of the leading edge of the brake pad during brake application(due to the leading edge's retention feature taking up the clearance inits lateral groove as its beveled surface meets the beveled top of thelateral groove) it may be desirable to provide a very corresponding verysmall relief or taper angle on the straight portion of the trailing edgeof the brake pad. Preferably the amount of clearance in the leading edgelateral groove is maintained large enough to ensure free pad movementtoward/away from the brake disc during all operating conditions, butsmall enough that when the pad rotates about the curved retainingfeature on the trailing edge the backing plate only rotates on the orderof three degrees or less (i.e., the trailing edge relief angle would beless than approximately 10 degrees, and preferably would be maintainedat three degrees or less, very preferably approximately one degree).

A time- and labor-saving method of installation of brake pads in a newbrake embodiment of the present invention would include a first step ofsliding the as-yet pad-less brake caliper axially outward to position hebrake for receipt of the outboard brake pad. A second step would involveinserting radially inwardly the outboard brake pad until the brake pad'slateral retention features are aligned with the lateral receivingfeatures in the outboard side of the brake pad carrier. A third stepwould involve sliding the caliper in the axially inward direction toboth advance the outboard brake pad into engagement with the carrier'soutboard side pad receiving features, and to position the caliper forreceiving the inboard brake pad. A fourth step would involve insertingradially inwardly the inboard brake pad until the brake pad's lateralretention features are aligned with the lateral receiving features inthe inboard side of the brake pad carrier. A fifth step would involveadvancing the brake application and/or adjusting mechanisms in the brakeapplication direction to both advance the inboard brake pad intoengagement with the carrier's inboard side pad receiving features, andto position the caliper for brake operation. The thickness of the brakepad retention features and the arrangements of the correspondingreceiving features must be such that sufficient brake pad retentionengagement is always ensured, even when the brake pad and the brakerotor are new, i.e., at their maximum thicknesses before use.

In the case of replacing brake pads in, for example, an in-service brakein which brake pads are already installed, the foregoing brake padloading method would be prefaced with a corresponding brake pad removaloperation, in which: the brake application and/or adjustment mechanismsare withdrawn far enough to permit the inboard brake pad to be movedaway from the brake disc to reach the brake pad removal position, theinboard brake pad would be extracted radially outward through thecaliper aperture, the caliper would be moved in the radially outwarddirection far enough to permit the outboard brake pad to be moved awayfrom the brake disc to reach its brake pad removal position, and theoutboard brake pad would be extracted radially outward through thecaliper aperture.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. For example, rather thanmachining vertical and lateral grooves 11, 12 in the mounting horns 10,a replaceable pad abutment surface may be provided on the carrier mount4, with a width and height corresponding to the geometry of theretaining features on the brake pad backing plate 14. As anotherexample, more than one pad retaining feature and corresponding receivingfeature on the caliper may be provided on each of the lateral sides ofthe brake pad, and/or the features may be provided at different heights.Because other such modifications of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and equivalentsthereof.

What is claimed is:
 1. A method for installing a brake pad into a discbrake comprising a brake caliper, a brake pad carrier and a brake disc,the caliper being configured to straddle the carrier and the disc, thebrake pad having a radially outer and a radially inner edge and opposinglateral edges between the radially outer and inner edges, comprising theacts of: aligning the brake pad with at least one radially-orientedbrake pad insertion feature in the disc brake, the brake pad beingoriented as when the brake pad is in an installed position and having atleast one pad retention feature on at least one lateral edge of thebrake pad, the at least one pad retaining feature on at least onelateral edge of the brake pad being configured to retain the brake padagainst radially outward motion when the brake pad is in the installedposition; moving the brake pad in a radially-inward direction through abrake pad opening of the brake caliper when the brake caliper is in anoperating position on the disc brake while maintaining the brake padoriented as when in the installed position until the at least one padretention feature of the brake pad is aligned with at least one lateralbrake pad receiving feature of the disc brake oriented parallel to abrake disc rotation axis; moving the brake pad toward the brake disc toengage the at least one brake pad retention feature with the at leastone lateral brake pad receiving feature.
 2. The brake pad installationmethod of claim 1, further comprising the act of: retracting a brakeapplication device of the caliper to a position sufficiently away fromthe brake disc to permit the brake pad to be inserted in aradially-inward direction without interference from the brakeapplication device.
 3. The brake pad installation method of claim 2,further comprising the act of: advancing the brake application devicetoward the brake pad to prevent disengaging of the at least oneretaining feature of the brake pad from the at least one lateral brakepad receiving feature.
 4. The brake pad installation method of claim 1,wherein the at least one radially-oriented brake pad insertion featureand the at least one lateral brake pad receiving feature are provided onboth opposing brake pad retention surfaces of the carrier, and the brakecaliper includes a brake pad opening sufficiently wide in thecircumferential direction of the brake disc to permit the brake pad topass through the caliper brake pad opening into the radially-orientedbrake pad insertion grooves without removal of the caliper from over thecarrier.
 5. The brake pad installation method of claim 4, wherein the atleast one brake pad retention feature and the at least one lateral brakepad receiving feature include features on laterally-opposite sides ofthe brake pad, and the brake pad retaining features are male projectionsand the lateral brake pad receiving features are female grooves.
 6. Thebrake pad installation method of claim 4, wherein the at least one brakepad retention feature and the at least one lateral brake pad receivingfeature include features on laterally-opposite sides of the brake pad,and the brake pad retaining features are female grooves and the lateralbrake pad receiving features are male projections.
 7. The brake padinstallation method of claim 4, wherein the brake pad carrier isconfigured to receive the brake caliper as a caliper mount.
 8. The brakepad installation method of claim 4, wherein the at least one brake padretention feature includes two brake pad retention features, each of thetwo brake pad retention features is arranged on opposite sides of thebrake pad, and the two brake pad retention features are asymmetric.
 9. Amethod for installing a brake pad into a disc brake comprising a brakecaliper, a brake pad carrier and a brake disc, the caliper beingconfigured to straddle the carrier and the disc and having a brake padopening sufficiently wide in the circumferential direction of the brakedisc to permit the brake pad to pass through the brake pad opening in aradially-inward direction without removal of the caliper from over thecarrier, the brake pad having a radially outer and a radially inner edgeand opposing lateral edges between the radially outer and inner edges,comprising the acts of: aligning the brake pad with the brake padopening, the brake pad being oriented as when the brake pad is in aninstalled position and having at least one pad retention feature on atleast one lateral edge of the brake pad, the at least one pad retainingfeature on at least one lateral edge of the brake pad being configuredto retain the brake pad against radially outward motion when the brakepad is in the installed position; moving the brake pad in aradially-inward direction through a brake pad opening of the brakecaliper when the brake caliper is in an operating position on the discbrake while maintaining the brake pad oriented as when in the installedposition until the at least one pad retention feature of the brake padis aligned with at least one lateral brake pad receiving feature of thedisc brake oriented parallel to a brake disc rotation axis; moving thebrake pad toward the brake disc to engage the at least one brake padretention feature with the at least one lateral brake pad receivingfeature.
 10. The brake pad installation method of claim 9, furthercomprising the act of: retracting a brake application device of thecaliper to a position sufficiently away from the brake disc to permitthe brake pad to be inserted in the radially-inward direction withoutinterference from the brake application device.
 11. The brake padinstallation method of claim 10, further comprising the act of:advancing the brake application device toward the brake pad to preventdisengaging of the at least one retaining feature of the brake pad fromthe at least one lateral brake pad receiving feature.